JPH0213014B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for binding small-grained iron powder recovered from slag. Prior art and its problems Of the iron particles recovered from blast furnace slag, coarse particles can be easily recovered and reused as raw materials for steelmaking. However, fine particles, especially those smaller than 1 mm, are not only difficult to collect, but also difficult to handle before they can be put into the furnace where they can be collected. , which becomes a burden on the dust collector. Therefore, there is currently a problem because these fine iron particles are not used effectively. In order to effectively use such slag recovered iron powder, it is preferable to bind the iron powder with a suitable binder to form iron pellets. On the other hand, as a method for preventing the generation of dust during transportation of iron ore, there is a known method of binding the dust with Portland cement, pitch, or the like. However, when binding slag recovered powdered iron with these binders, it is necessary to avoid interparticle voids because the powdered iron has a relatively uniform particle size and is not flat, but close to spherical in shape. is large and requires a large amount of binder, which is not only uneconomical but also depends on the type of binder, such as cement.
The quality of powdered iron will deteriorate significantly. Means for solving the problems The present invention provides powdered iron recovered from slag with an average particle size of 0.005 to 3.
mm of slag slag and/or fine iron powder from 1 to 1 mm of the total amount
30% by volume and binder 0.1-3% by weight of the total amount
This invention relates to a slag recovery powdered iron binding method characterized by adding (in terms of pure content), kneading, and press molding. Slag recovered powdered iron to which the present invention is applied is powdered iron recovered from steel slag, iron manufacturing slag, desulfurization slag, etc. This powdered iron has a narrow particle size distribution and large interparticle voids. Iron content is approximately 90% or more, usually 95% or more, and it is hoped that this can be used effectively. Powder particles with a flat shape, such as iron and steel powder, are deformed by high-pressure molding, so they can be agglomerated even with a small amount of binder or no binder. However, the slag recovered powdered iron to which the present invention is applied has a nearly spherical shape and the interparticle voids become large, making it difficult to agglomerate only by high-pressure molding and requiring a large amount of binder, which is not preferable. There are the following four processes for utilizing powdered iron agglomerates. ) Molding of powdered iron (agglomeration molding) ) Curing of molded products (stocking) ) Transportation of molded products (handling) ) Consumption Must be high. The present inventors used various binders to bind powdered iron under various conditions and measured the strength after curing for a certain period of time, and found that the binders shown below are effective. It became clear. Examples of organic binders include thermoplastic resins such as polyvinyl acetate, polyvinyl alcohol, and acrylic polymers, thermosetting resins such as polyurethane, epoxy resins, phenol resins, furan resins, urea resins, and melamine resins. . Although it is preferable that the curing period be short, powdered iron has lower strength than flat granular materials, and it is difficult to maintain the molded state unless a certain level of strength is applied immediately after molding. A monomeric polymer having a vinyl group is preferable as a low-cost binder that achieves a certain level of strength immediately after molding, and these bind with powdered iron and provide strength during a short molding time. I understand. Preferred polymers of vinyl group-containing monomers include:
For example, polyvinyl acetate, polyvinyl alcohol,
Examples include acrylic polymers such as polyacrylamide, polyacrylic or partially saponified methacrylic acid esters. If necessary, these resins may be formalin crosslinked to improve water resistance. Considering the corrosivity of iron, polyacrylamide is particularly suitable than saponified partial esters. Of course, in such cases, a rust preventive may also be used. The appropriate amount of the binder to be used is 0.1 to 3 parts by weight, more preferably 0.3 to 1 part by weight, based on the pure content. This adhesive is used to provide strength immediately after molding. If it is necessary to provide even higher strength after curing for a certain period of time, this adhesive can be used alone or in combination with other binders. You may. In the present invention, in addition to the binder, the average particle size is 0.005 to 3 mm.
1 to 30% of the total amount of slag slag and/or fine iron
By using % by volume to fill the voids, it became possible to save on binder and facilitate molding. The fine powder is smaller than the average particle size of powdered iron, and is 1/3 or less, more preferably 1/10 or less. Since the slag recovered fine powder iron itself is effectively used, there is no waste, and it is preferable as the fine powder iron. Although the purity of powdered iron is lower, slag slag is the most commonly used material both economically and practically. If the amount of fine powder such as slag slag and/or fine iron powder is less than 1% by volume, it is not effective in reducing the amount of binder used. Although it may be used in an amount of 30% by volume or more, it is not preferable because fine powder may cause a decrease in purity and an increase in price. More preferably 2-10
It is capacity %. Add the binder and fine powder to the slag recovered powdered iron, knead until sufficiently uniform, place in a container of a specified size, and heat at room temperature or under heating, e.g. 10 to 200℃, to approx.
Pressure molding is carried out at a pressure of 0.5 to 10 ton/cm ² , more preferably 2 to 5 ton/cm ² . Although it is possible to obtain a molded article with less than 0.5 ton/cm ² , the predetermined initial strength cannot be obtained, and when molded with more than 10 ton/cm ² , the equipment becomes large and running costs increase. In addition to the above-mentioned press forming, the pressure forming may be carried out by pressing while vibrating or by using a briquette machine. The pressed compact of slag recovered powdered iron obtained by the method of the present invention becomes an agglomerated product that already has sufficient strength immediately after compacting. The thus obtained agglomerates can be used as raw materials for steelmaking, coolants, and the like. The present invention will be explained below with reference to Examples. Example 1 Mix 50g of two types of powdered iron recovered from slag having the particle sizes shown below with the fine powder shown in Table 1, add a predetermined amount of an aqueous solution of polyvinyl alcohol or polyacrylamide to the mixture, place it in a beaker, and mix it with a glass rod. Mix thoroughly and mold as shown in Figure 1 (25φ cylinder).
37g was transferred and pressure molded. In the figure, 1 is a sample, 2 is a mold, and 3 is a pressure head. The pressure-molded agglomerates are subjected to a second process immediately after forming, 10 minutes, 20 minutes, and 24 hours later.
The crushing strength was measured using the apparatus shown in the figure. In the figure, 1 is a sample, 4 is a press, and 5 is a pedestal. The crushing strength was measured by placing the sample on a pedestal, gradually applying pressure with a press from the circumferential direction, and reading the pressure when the sample broke. The binder composition and results of the samples are shown in Table-1. The particle size of the slag recovered powdered iron was as follows. Powdered iron A 9 mesh pass 100% passage 12 mesh pass 98.2%〃 16 mesh pass 69.7%〃 32 mesh pass 15.8%〃 100 mesh pass 0.1%〃 (Average particle size: 0.85m/m) Powdered iron B 3.5 mesh pass 99.7% passage 5 mesh Pass 92.0 〃 8 mesh passes 42.1 〃 16 mesh passes 4.2 〃 (Average particle size: 2.6m/m)

[Table] Effects of the invention Particle size recovered from slag by the method of the invention
Powdered iron of about 0.1 to 3 m/m can be bound using a small amount of binder. As a result, powdered iron, which had been removed by a dust collector due to poor handling or when being fed into the furnace, can be agglomerated at low cost and can be effectively recovered and reused.

[Brief explanation of drawings]

Figure 1 shows the mold, and Figure 2 shows the crushing strength tester. 1... Sample, 2... Mold, 3... Pressure head, 4... Press, 5... Pedestal, respectively.

Claims (1)

[Scope of Claims] 1. Slag slag and/or fine iron powder with an average particle size of 0.005 to 3 mm is added to the recovered slag powder iron in an amount of 1 to 30% by volume of the total amount, and an organic binder is added in an amount of 0.1 to 3% by weight of the total amount (purity). A slag recovery powder iron binding method characterized by adding (conversion), kneading, and press-forming. 2. The slag recovered powdered iron binding method according to item 1, wherein the slag recovered powdered iron has an average particle size of 0.3 to 10 mm. 3. The slag recovery powdered iron binding method according to item 1, wherein the binder is a monomeric polymer having a vinyl group. 4. The slag recovery powdered iron binding method according to item 3, wherein the vinyl group-containing monomer polymer is selected from polyvinyl acetate, polyvinyl alcohol, and acrylic polymers.